Method of using lignin for introducing water into vulcanizable compositions



T. R. GRIFFITH ETAL METHOD OF USING LIGNIN FOR INTRODUCING,

WATER INTO VULCANIZABLE COMPOSITIONS Filed 001.. 1. 1953 Oct. 21, 1958 2,857,345

N 53 Zfrzcrease in modulus.

/ maisfare Conierz'z of Zigvzz'rz Effect of moisture Content f Zz'qnz'n on modulus (12' 5002 Elongation.

I rel/67220719 Thom as 72. Griff-i Zh United States atent Ofitice 2,857,345 Patented Oct. 21, 19.58

METHOD OF USING LliGNlN FUR INTRODUCING WATER INTO VULCANEZABLE COMPOSITIUNS Thomas Raymond Griflith, Ottawa, ()ntario, Canada, and DonaldWesley MacGregor, Cornwalli, @ntario, Canada, assignors, by mesne assignments, to Howard Smith Paper Mills Limited, Montreal, Quebec, Canada Application October 1, 1953, Serial No. 383,618 3 Claims. (Cl. 260-175) This invention relates to improvements in vulcanization and more particularly it relates to novel lignin compositions and use thereof as a means of incorporating water into vulcanizable masses. This is a continuation-in-part of application Serial No. 313,808, filed October 8, 1952.

It'has long been known that the presence of water in vulcanizable masses has a pronounced elfect upon the rate of vulcanization as well as upon the characteristics of the vulcanizate produced. While such effects are particularly outstanding in the vulcanization of materials which require the addition of sulphur to the formula to-be vulcanized, some eifect is present in all vulcanization reactions.

Although the exact mechanics of vulcanization are not fully known, it is believed that the effect of water during vulcanization can be attributed mainly to the fact that at least one ionic reaction must take place during vulcanization,-which reaction will proceed more uniformly and will be greatly accelerated in the presence of water.

Various articles have been published on the subject of theelfect of water upon particular vulcanization reactions among which might be mentioned that by Braendle and Wiegand, vol. 36 (August 1944), Industrial and Engineering Chemistry, No. 8, pages 724-727. This article reports an investigation into the effect of the presence of water during the vulcanization of butadiene-styrene formulations known in the trade as GR-S compounds and the authors concluded that variation in moisture content of the formulation is one of the chief reasons for the variation in curing time which had been encountered with GR-S compounds.

While it has as above mentioned been long recognized that moisture plays an important part in vulcanization reactions, the control of moisture in vulcanization formulations has in practice been found to be most diificult because of the physical characteristics of the substances into which the water must be introduced. In the abovementioned article, for instance, Braendle and Wiegand introduced water in the carbon black. This method of introduction, however, is not satisfactory because, as is also mentioned in the article referred to, carbon .black has a high afiinity for water up to its natural absorptive capacity and the water which is absorbed by it is apparently fixed in such a way that it is not available to take part in the vulcanization reaction. Moisture present in excess of the absorptive capacity of the carbon is present as wet moisture and is subject to the usual difiiculties of introduction into the formulation. Further, while it may be possible by using carbon black as a carrier for water to measure accurately the amount of water intro duced to the carbon black, it has been found in practice that the length of time required to mill the formulations to uniformity, and the elevated milling temperatures encountered, will cause loss through evaporation of an indeterminable amount of water, thus making it virtually impossible to predetermine the amount of water which is actually introduced. into the formulation.

The present invention has as its principal object the provision of a novel method for uniformly introducing into vulcanizable elastomer compositions anaccurately predetermined quantity of water..

Various other objects and advantages of the invention will become apparent as the specification proceeds.

The present invention is based upon the discovery that certain precipitated lignins have high afilnity for moisture and are capable of carrying in certain cases up to of their own weight in water while retaining the physical characteristics of finely divided freely flowing dry. powders which are capable of being milled into vulcanizable masses in the same manner as a normal'filler. These lignins, while they will retain moisture in the above manner, are not themselves hygroscopic so that what water they carry in the above manner is water which is available to the reactions proceeding within the mass during the vulcanization process.

Not all lignin compositions which are looselydesignated in the art as lignin exhibit the above properties asthe physical properties of such compositions vary widelydepending upon their source and the chemical treatments to which they have been subjected. Three criteria are essential'in lignins which are tobe used in accordance with the present invention.

('1) The ligniu must be water insoluble, that is to say such soluble lignin compositions as sodium lignate, lignin sulphonate and etc. cannot be used.

(2) The lignin must be in an appropriate physical state wherein it is capable of carrying a substantial proportion of water while yet remaining a freely flowing powder.

(3) The lignin must be free of entrained acid so as not to interfere with the vulcanization reaction to which the water is to be added in accordance with the present invention.

Those lignins which we have found to be useful in accordance with the present invention are finely divided lignins isolated by precipitation from the aqueous liquors obtained from the alkaline digestion of lignocellulosic materials. Highly suitable lignins are, for instance, those prepared in accordance with the teachings .of United States Patent 2,406,867 and those commercially available under the trademark Indulin A of The West Virginia Paper Company. The suitability of any particular lignin for use in the present invention depends primarily upon the conditions under which the lignins are precipitated and filtered from the lignin-bearing solution. How ever, satisfactory lignins may be prepared for use in the invention from those which are otherwise unsuitable by dissolving the lignin in alkaline solution and re-precipitating under suitable conditions as hereinafter described.

it is known in the art that the precipitation of lignin by the acidification of an alkaline solution thereof is subject to considerable ditliculty unless proper conditions are observed because of the fact that if the solution is below a certain critical temperature range, called the optimum pre-filtering range (which varies from one lignin to the other) filtration and washing become progressively more ditficult.

If the acid precipitation of the lignin is carried out at temperatures substantially lower than the optimum prefiltering range, and the precipitated mixture is not further heated to a temperature within the optimum pro-filtering range before filtering, gelatinous type precipitates are .obtained that are extremely difiicult to filter and wash. In this connection it is to be noted that once having been heated to within the optimum pre-filtering range the .precipitated mixture may be cooled before filtration without materially affecting its filtering characteristics. With unoxidized lignin, a temperature of 9395 C. permits readly filtration and washing while still maintainingthedesired 3 properties in the product. It is immaterial whether this temperature is reached during or subsequent to actual precipitation, and it is not necessary, as mentioned above that this temperature be maintained until the time of filtration. If the maximum temperature before filtration is too high, the lignin will melt in contact with water even though this temperature may be materially lower than the melting point of the dry lignin. It has been found that this reduction in melting point which presumably results from water dissolved in the lignin will be as much as 80 C. or more lower than the melting point of the dry lignin. With an unoxidized lignin, it has been found that the maximum temperature before filtration should be no greater than 96 C. since otherwise the lignin will melt and coalesce.

With oxidized lignins, similar phenomena exist, but the specific temperatures are of a higher order than with unoxidized lignin. For instance, with the oxidized lignin described in Example 2 below a maximum temperature before filtration of 112 C. was found to give good filtering and washing characteristics whereas the temperature of 95 C. used for the unoxidized lignin in Example 1 would be too low and a maximum temperature of 127 C. would result in a melting of the lignin in the presence of water.

With lignins of intermediate degree of oxidation, the optimum pre-filtering range lies between the optimum filtering ranges of unoxidized lignin and that of the relatively highly oxidized lignin prepared in accordance with Example 2 and a satisfactory filtration temperature will lie somewhere between those indicated for oxidized and unoxidized lignin depending upon the particular degree of oxidation in each case.

The acid precipitation of the lignin and the preparation of the moisture-containing powder can be carried out in the following manner. The alkaline solution of the lignin is heated to a temperature of approximately 50 to 80 C. if the lignin is unoxidized, and somewhat higher, say 70 to 100 C. if oxidized. The lignin is then precipitated, under agitation, by the addition of a dilute acid such as sulfuric, or hydrochloric acid, preferably at a pH of approximately 2.5. To facilitate subsequent filtering and washing the resultant suspension may be further heated to a temperature of 80 to 95 C. with the unoxidized lignin and to 95 to 125 C. with the oxidized lignin, temperatures higher than the normal boiling point being obtained by heating at superatmospheric pressure. The precipitate is then filtered and thoroughly washed with water following which it may be throughly dried, and subsequently mixed with a predetermined quantity of water to produce the freely flowing water containing lignin compositions for use in practising the invention or only partially dried to a moisture content of predetermined degree. Since the lignin is not hygroscopic, it should be kept in a tightly stoppered container once its water content has been adjusted to the desired value.

The following examples illustrate the preparation of suitable lignins both directly from the liquors obtained from the alkaline digestion of lignocellulosic materials and by the dissolving and re-precipitating of otherwise unsuitable lignins.

EXAMPLE 1 Preparation of unoxidized lignin In accordance with the teachings of United States Patent 2,406,867, black liquor resulting from the alkaline digestion of poplar wood was spray-carbonated at a temperature of 70 C. until a pH of 9.5 was reached with flue gas under conditions such that the maximum dwell time of the liquor in contact with the flue gas was of the order of only 30 minutes to minimize oxidation from the minor content of oxygen in the flue gas. The lignin acid salt which precipitated from the liquid was separated by heating the carbonated liquor at 95 C. at which temd perature the precipitate coalesced into a tar which was separated by continuous decantation. The lignin salt was dissolved in hot water to give a solution containing 12% acid precipitatable lignin.

Unoxidized lignin was directly precipitated from this solution at a temperature of C. with vigorous agitation by the continuous addition of this solution to a precipitating medium maintained at a pH of 2.5 by the continuous addition of sulphuric acid. A continuous overflow of the precipitated slurry was after-heated to C. and filtered on a continuous rotary vacuum filter. The product was washed on the filter and then flash dried with hot air at 735 C. One hundred parts of the dried product could be mixed with 75 parts of water while yet retaining the characteristics of a free-flowing powder suitable for use as an agent for carrying water into vulcanizable masses in accordance with the present invention.

EXAMPLE 2 Preparation of oxidized lignin The lignin acid salt solution referred to in Example 1 and containing 12% acid precipitatable lignin was placed in a tank of 11' 6" diameter to a depth of 17 6". The tank was equipped with an air distributor at the bottom. The temperature of the liquid was maintained at 70 C. and air at a rate of 200 C. F. M. was bubbled through the solution for 4% hours. The pH of the liquid was maintained at 10.0-11.2 during the addition of air by the periodic addition of sodium hydroxide. The lignin was then precipitated from the oxidized liquor and filtered and washed using the same technique and equipment as used for the filtration and washing of the unoxidized lignin of Example 1 with the exception that a precipitating temperature of 95 C. was maintained and the product was after-heated before filtration at super-atmospheric pressure to a temperature of 112 C. The dry oxidized lignin thus produced could be mixed with 125% of its weight of water while still maintaining the characteristics of a free-flowing powder suitable for use in the introduction of water to vulcanizable compositions in accordance with the present invention.

EXAMPLE 3 Preparation 0) suitable lignins by res-precipitation One hundred parts of dry lignin (marketed by The Mead Corporation of Chillicothe, Ohio, under the trademark Meadol) was dissolved in 890 parts of water with the addition of 10 parts of sodium hydroxide to convert the lignin to its soluble sodium salt. The solution was heated to 90 C. and dilute hydrochloric acid was then added with vigorous agitation until the pH was lowered to 2.5. The precipitate was filtered and washed on a Biichner funnel and air was sucked through the filter cake until it appeared dry and had the consistency of a freely-flowing powder. Following this a water content determination was made, indicating that the filtered cake contained 68 parts of water per parts of lignin. Milling tests indicated that the filter cake material would mill satisfactorily into rubber compositions in accordance with the process of the present invention. Milling tests with the same lignin prior to treatment in the above manner indicated poor milling qualities whenever the lignin was mixed with an amount of water approaching 50 parts water per 100 parts of lignin.

The above procedure may be used to improve the water carrying abilities of most lignins which, in their initial state, are not capable of carrying sufficient water while remaining freely-flowing powders to be used effectively for purposes of the present invention. It will be appreciated that soluble salts of lignin can be used as the starting material in which case, of course, the addition of alkali may not be necessary for purposes of preparing thesolution from which .thedignin isto be precipitated. It will be further appreciated, however, that acid soluble 'lignins, such as lignin sulphenate and the like, cannot be treated satisfactorily by the above method since they do notrprecipitate :fromacidsolution.

In carrying out the re-precipitation lof lignin in the above manner on lignins from various sources, it was found that optimum filtering conditions occurred at differenttemperatures for each individual type of lignin. It is, therefore, desirable when preparing lignins for use in the present invention using the above procedure to run ,one or more small scale precipitation tests so that a suitable temperature for precipitation and filtration may be determined for the particular material which is to be -treated.' A suitable precipitating and filtering temperature is indicated by the formation of a granular precipitateiwhich is not of gelatinous appearance and which does not adhere to the vsides of the vessel in which it is precipitated or coagulate in agglomerated lumps.

It will be understood that the lignin which is obtained in accordance with the above examples after fitlration and washing but before drying may be used directly for the process of the present invention without any intermediate drying stage. Alternatively, the dried lignin can be slurried in 'hot water and refiltered, or the water may be added directly to the lignin in a tumbling blender.

In using these lignin compositions for purposes of the invention for introducing water into-yulcanizable formulations, a conventional formulation is prepared accord- ;ing to known means and the lignin composition is added in suificient amountto provide the :quantity of .water which it is desired to have present. If the ultimate product of vulcanization is to be a substantially unfilled material, it is desirable to use a lignin composition cont-aining a maximumproporton of absorbed water so that thereqilired amountof water will be introduced utilizing the minimum amount of lignin. The lignin itself is inert during the vulcanizing reaction, butit has such a high afiinity for rubber and other polymerizable materials that it disperses thoroughly and uniformly throughout the formulation during the milling thereof and carries the water it contains uniformly and thoroughly-into intimate contact with the material of the formulation throughout the mass thereof. Since the water-carrying -ligninflcompositions have the physical characteristics of adry freeflowing powder, no more difiiculty is encountered in incorporating them uniformly with their ,contained water into a mass of vulcanizable materiai than is encountered in incorporating any conventional dry filler or other material, such for instance as whiting. Moreover, substantially all of the water contained in the (ligningcomposi-I tions is incorporated in the mass so that. the amount of water thus incorporated can be controlled with accuracy.

The addition of ordinary lignin to vulcanizable materials is, of course, not new, and its use as a reinforcer is well known in the art.

forcer is coprecipitated with the material which is to be vulcanized, the lignin remains inert and has no elfect upon the vulcanization. Thus, in some cases, ordinary powdered lignin has .been .usedas a filler from time to time in place of more conventional fillers when its use inthis respect has'been rendered advantageous fromwa n economical standpoint. p

The invention will be understood with greater particularity from a consideration of the data in the following examples and in the drawing wherein Figure 1 is a graph illustrating t he effectof lignin-introduced moisture upon the increasein modulus produced. 4,

i The examples given below of standard type formula- ,tions nsed'in the vulcanization of both natural rubberjand ,GR-S, with and without oxidized lignin as a water carrier, show theefiectiveness of lignin as a water carrier The anomaly has been noted however, that unless the lignin to be used as a rein- 6 and, therefore, as a means of speeding up the rate of vulcanization.

Whennatural rubber is masterbatched with lignin it is extremely difiicult to obtain a satisfactory cure. By 5 the method of the present inventionthe rate of cure can be markedly increased while at the same time compounds of higher tensile strength are obtained.

l0 EXAMPLE 4 Parts by weight a w I, i V 1 Natural Rubber (in lignin iuasterba'tch) .L. ,100 Lignin (in lignin inusterbatch) 1 x50 Stea-ric Acid 2 Zinc Oxide... '5 Ziinate... 1.. Santoeuie .1), 5 2O Sulphur 2 Moist Oxidized Lignin:

Lignin content; 6. 8 Moisture content: 3. 2

V 160. 5 165.5 Percent Moisture-by-analysis, on uncured'stockm -0:95' 8:33

rubber and parts lignin.

150 parts lignin masterbatch (33.3%'1ignin) consisting of 100 parts 2 Contains 32 percent moisture.

. Thetiguresin' Table 31 show-{the increased tensile 45 strength obtained by the incorporation of lignin as a water carrier into the formulation as well as the greatly enhanced rate of cure in the vulcanization of natural rubber. The stock without lignin as a water carrier did not appear to have been completely cured in 40'minutes 59 whereas the -.st o t:k with .the carrier reached its maximum tensile streng'thin 10 minutes.

Example 5.

EXAMPLE 5 r Parts by Weight GR-S (in lignin masterbatch) 1 72. 2 72. 2 Lignin (in ligmin masterbatch) 1 36.1 36.1 GR-S Z 27. 8 27.8 Stearic Acid. 2 2 Zinc Oxide 5 5 Benzothiazole disulphide (Altax) accelerator (R. '1. Vanderbilt O0.) 1.5 1. 5

Copper di nethyl dithiocarbamate (Oumate),

accelerator (R. T. Vanderbilt Co.) 0. 1 O. 1 ulphur 4 4 Moist oxidized Ligiin- 3 Lignin content 6. 8 Moisture content. 3. 2 14s. 1 158.7

Percent Moisture, by analysis, on uncured stock 1, 9 3. 38

150 parts lignin masterbatch (33.3% lignin) containing 100 parts (311-8 and 50 parts lignin.

2 Added to make rubber equal 100. 3 Contains 32% moisture.

, his effect with GRS,{lignin masterbatch is shown in TABLE 2 The effect of adding small amounts of lignin and mois- Tensljle p S i ture is to markedly increase the tensile strength of the compound as can be seen from a comparison of Formula- Curetime at 282 F., minutes without \vijtlh ligtion 6 with Formulation 5 of Table 3. However, as the ii in n 353 22.33? a carrier qu'antlty of lignin and moisture added to the stock 1s mr (3) (4) creased the gain in tensile strength becomes somewhat less (Formulation 7) or may result in a slight loss (Formula- 3 23% 10 tion 8) compared with the standard compound. The @22 8 moisturecont'aining lignin has the effect of increasing the 1 rate of cure as indicated by the time to reach a given The figures in Table 2 also show an increased tensile modulus. At the same time an increase in tear strength strength obta ned in a much shortenculillng i e 1 t is observed while the permanent set at break is decreased. g gi of hgnm as a water Gamer m t e camzatlon in Example 7 a high abrasion furnace black was used as Moisture-containing lignin can also be used to advanremfomng f h f the efiect of addmg tage with GR-S compounds when the reinforcing agent is both y and meet 113mm was mvestlgatedcarbon black, Example 6 indicating the result obtained no with channel black.

' EXAMPLE 6 EXAMPLE 7 (5) (6) (7) (8) Parts by weight 25 GRS 100 100 100 100 Roegen, as cizer (Vanderbilt 00.). 5 6 5 5 (1 fii s?"(375155""5 5 5 5 5 cr ne an ar y 100 100 100 siffifiefin ofti ifiBiff??? 50 50 50 50 Phflblack 01.111511 abrasmn furnace (HA1?) Benzothiozole disulphide (Altax), lumps Petmleum accelerator 30 B l t 1 1355-5513 5555255351-55 2 2 2 gggg g ditmocarbamate" :3 N-eyclohexyl2-benz0thiezole sulfenamide MOM iia' i am'j gfi antocure), ac elerator 0.7 0.7 0.7 Lignln content 63 5 2 9 g g gi g fi ga 15:1 2 2 2 Moisture content 2. 37 4.7 .1 1165511? y] 6 8 015 we con en 3.2 w 153.55 153. 55 173.55 173.55 35 Omizedfignm (moisture man" Percent Moisture, by analysis, en un cured stock" 0.29 1.67 2. 92 3.90

1 Contains 47.4% moisture. 1 Contains 32% moisture.

TABLE 3 7 Curetime Stress Tensile Eiong- Shore Bashore Perm. Graves Formulation No. in min. at Strength, ation, herdresilset at tear, V at 287. F. 300% p. 5.1. percent ness ienee break, 1b./i.n.

pereent TABLE 4 Formula- Curetime Stress at Tensile Elonge- Shore Bashore Graves tion N0. mmin. at 300% strength, tion, hardness resilience tear,

287 F. p. s. 1. percent 1b./in.

20 855 3,035 540 53 35 245 (9) 30 1, 3, 200 450 55 35 233 40 2, 2, 730 400 55 37 234 50 2, 270 2, 925 330 55 37 230 20 880 1, 350 570 51 55 230 (10) 30 1,300 2, 490 510 55 35 24s 4o 1, 570 2, 555 470 55 35 251 50 1, 355 2, 320 440 57 37 247 20 1, 300 2, 550 550 54 35 250 (m 30 1, 545 2, 875 510 55 55 249 40 1, 725 3, 015 450 55 37 245 50 1, 740 2, 985 470 57 37 242 But. b .a tai te n Fabl 4 i manner i tc 1. a e- I t l U 9. liow v gth ad ft bn .Qf th m9. tum out ti e i n r ult 'i en 41e r tt ll en wm e wit liheus p -mo t EXAMPLES V The .eflfectiveness of unoxidized lignin as a water "car- .rier.is shown. i

free ,l ignin. Theicon rpdund with moisturercontaining a ts bywe t lign n i, hows a somewhat .more rapid cure, as indicated by the time taken to reacha modulusof 1000 11 5. pereg. (l5) & a 5.00% e q a ee t -thqs wm e n to wh Water has not been added.- It also ;shows a steadier h .92 modulusasghe time ofcure creas d, as comparedwith 5 the standard compound, i. e. lyla r chin g n odulus has 5 been prevented. The elongation at break also remains 0115 20 more qnfitema t taflmeo cu e is in easedg incon en 3.1 .EXQMPLE 8 Moisture content 1.0 f t ee fept veness .Q li ni a a wate c rrier on the e 68.05 ulq piz t e a .Q utediet eracry qni r e cop y tHy a .,,1S--. l- QW.1. 1 Contains 38,7%moisture.

Cure Stress Tensile Elonga- Shore Bash rle l Perm Graves Formulation No. timein at strength, tionat hardresilset at ar, min. at 300% p. s. i. break, ness ience break in lb./in. 287 F. percent percent 16 310 1, 005 740 42 3s 34 145 14 30 805 2, 380 020 55 34 219 45 1,175 2,975 510 59 a5 is 247 60 1, 530 2, 805 460 62 35 16 240 15 615 2, 320 740 54 35 26 220 15 1, 235 2, 910 650 02 15 249 1,410 3,180 500 65 as 14 281 00 1,575 2, 900 470 66 35 12 270 It is shown in Table 6 that the effectiveness of unoxi- Parts by Weight dized lignin as a water carrier is similar to that of oxidized lignin as .a water carrier. (12) (13) 40 The improvement in the vulcanization of rubber both natural and synthetic is illustrated in the fore oing ex- Hycar OR 25 100 100 amples. It results from the fact that liginn will carry Mlcronex 653d. (channel black) 2 water mto the compounded stock with ease. The water- Z f 5 5 carrying lignin is added with no more difiiculty, than Altai.-. 4 that experienced in the addition of a dry powder. No igg g g gai g gi tendency to porosity has been observed in this process.

Lignin Lignin, as a water carrier, permits the reduction of Mmstme con en organic accelerator in the formulation. Better physical 159-0 164-0 properties are obtainable than would result from in creased organic acceleration, and the rate of cure can Contains5 1 be more accurately controlled through the control of moisture.

The following example illustrates the effect of water introduced according to the invention upon rate of cure TABLE 5 and upon physical characteristics of the product contained in a typical formulation. Cure Stress Tensile Elonga- Shore Formulatime at strength, tlon at hard- Bashore EXAMPLE 10 tion No. 111 min. 300% p. s.i. break, ness resilience at 310 F percent Base formulation 1o 1 040 3, 760 520 07 10 Parts by weight (12) 2o 2 634 3,510 3 3 3 30 3,190 40 2,875 280 71 10 Reogen J 10 2,170 3,435 440 69 g Zm xi e 5 20 2 730 3,370 370 71 Micronex Std 1 (13) 30 2995 s, 310 71 10 5 i 40 2,895 270 71 1o Altax 1.5 Zimate 0.15 Sulphur 2.0 Oxidized lignin:

Lignin content 5.0 70

Molsture content Variable Varying quantities of moisture were added to the above formulation by means of lignin used as a moisture carrier.

In each mixing the quantity of dry lignin was kept constant, and the moisture was varied by changing the moisture content of the lignin. In this way the only difference between the mixings was in the amount of moisture added.

The various mixings were cured for 15, 30, 45 and 60 minutes at 287 F., and the effect of moisture was estimated from the average modulus for the four cures.

Figure 1 shows percent moisture in the lignin, plotted against percent increase in average modulus. Five percent moisture in the lignin shows a small or negligible increase. Between 15 and moisture there is a considerable increase in modulus and beyond 25 the increase tapers off.

What we claim as our invention is:

1. In the compounding of sulphur vulcanizable rubbery diene polymers and in which it is desired to have present during vulcanization a controlled percentage of water, the improvement which consists in; incorporating a predetermined =a.mount of water required to produce said controlled percentage in the rubbery diene polymer in a finely divided substance selected from the group consisting of unoxidized lignin which has been isolated by precipitation at a temperature of from about to about C. from the aqueous liquors obtained from the alkaline digestion of lignocellulosic material and oxidized lignin which has been isolated by precipitation at a temperature of from about 70 to about C. from the aqueous liquors obtained from the alkaline digestion of lignocellulosic material, so as to form a freely flowing powder of said water and said substance which contains from about 15 to about 150% by weight moisture; and then dry milling the thus formed powder into said elastomer composition whereby said water is carried into said composition and is available therein during vulcanization thereof.v

2. The improvement defined in claim 1 wherein the substance is unoxidized lignin. 1

3. The improvement defined in claim 1 wherein the substance is oxidized lignin.

References Cited in the file of this patent 15 UNITED STATES PATENTS 2,572,884 Pollak et a1. Oct. 30, 1951 2,608,537 Pollak Aug. 26, 1952 2,610,954 Ralf et al Sept. 16, 1952 20 2,760,943 Sohn Aug. 28, 1956 OTHER REFERENCES Paper Trade Journal, April 1, 1953, volume 116, No. 13, TAPPI Section, pages 136. 

1. IN THE COMPOUNDING OF SULPHUR VULCANIZABLE RUBBERY DIENE POLYMERS AND IN WHICH IT IS DESIRED TO HAVE PRESENT DURING VULCANIZATION A CONTROLLED PERCENTAGE OF WATER, THE IMPROVEMENT WHICH CONSISTS IN; INCORPORATING A PREDETERMINED AMOUNT OF WATER REQUIRED TO PRODUCE SAID CONTROLLED PERCENTAGE IN THE RUBBERY DIENE POLYMER IN A FINELY DIVIDED SUBSTANCE SELECTED FROM THE GROUP CONSISTING OF UNOXIDIZED LIGNIN WHICH HAS BEEN ISOLATED BY PRECIPITATION AT A TEMPERATURE OF FROM ABOUT 50 TO ABOUT 80*C. FROM THE AQUEOUS LIQUORS OBTAINED FROM THE ALKALINE DIGESTION OF LIGNOCELLULOSIC MATERIAL AND OXIDIZED LIGNIN WHICH HAS BEEN ISOLATED BY PRECIPITATION AT A TEMPERATURE OF FROM ABOUT 70 TO ABOUT 100*C. FROM THE AQUEOUS LIQUORS OBTAINED FROM THE ALKALINE DIGESTION OF LIGNOCELLULOSIC MATE- 